Where were you when the first astronauts landed on Mars? The answer to that question will be remembered by all those alive to witness such a historic event, but the astronauts who made the trip could very well struggle with it.

A new study published in Nature's Scientific Reports warns of the possibility of "space brain," or cognitive impairment or even dementia as a result of cosmic radiation bombarding the brain following an extended spaceflight. The findings show one more possible health hazard astronauts will have to contend with if they sign on for a mission to Mars.

So exactly what does constant bombardment by highly energetic charged particles do to the brain over the course of what would be a 2.5-year long mission to Mars?

Prolonged exposures can lead to a number of potential complications, such as "various performance decrements, memory deficits, anxiety, depression and impaired decision-making," according to study co-author Charles Limoli of the University of California - Irvine (UCI).

For their study, a team of UCI radiologists exposed rodents at NASA's Space Radiation Laboratory to charged particle irradiation (fully ionized oxygen and titanium), and then subjected the animals to brain scans as well as a series of six behavioral tests 12 or 24 weeks after irradiation, depending on the cohort.

Even upwards of six months after exposure, evidence of inflammation and neuron damage was present in the rodents' brains.

On the behavioral side, the team took particular notice of the detrimental effects of charged particle irradiation related to "fear extinction," or the brain's ability to suppress stressful associations. "The inability to moderate reactions to certain unpleasant stimuli could elicit elevated stress, anxiety and otherwise disadvantageous responses in unexpected or emergency situations," the researchers write.

"Such conditions could clearly be problematic for astronauts and their capability to efficiently operate over the course of a deep space mission," they continue in their study, "and impairments in executive function point to further potential complications in conducting complicated multifaceted tasks or in decision-making under stressful situations."

Given that it takes only months for the effects of "space brain" to start to show, mission planners will have to explore preventative measures, which may include engineering or pharmaceutical solutions, to protect astronauts.

"Our exploration of strange new worlds should not be hampered by the fear of cosmic radiation exposure, but rather, inspire robust efforts to advance our understanding of a previously unrecognized problem."